What is the best way to answer questions with a x expression in the question. for example 3x + 10x=?

Aflute is on sale for 20% off. including the discount and 8% tax, the sales price is $216.

Water flows at a steady rate from a tap. its takes 40 seconds to fill a 4 litre watering can from the tap. the rate at which water flows from the tap is halved. complete: 4 litres into cm3

A0.40 kg soccer ball is kicked so that its incoming velocity of 5 m/s is changed to an outgoing velocity of -25 m/s. what impulse does the player apply to the ball?